installed a dual exhaust and have heard that i need to reset the computer, my ? is if i need to how and why. Thanks

 

Can't help you with Why, but can help with the How.

Turn everything off. Remove only the Negative battery cable. Turn the headlights on for 5 minutes. Turn headlights off. Reconnect the Negative battery cable.

That's it!

 

You don't need to pull the battery, and lose all the radio presets and everything. You can just pull the fuse for the module in the power distribution box. I would think that resetting the computer would reset the data in the O/F calculation and allow the computer to compensate for the new larger exhaust.